Laparoscopic surgery requires several small incisions in the abdomen for the insertion of trocars or small cylindrical tubes approximately 5 to 10 millimeters in diameter through which surgical instruments and a laparoscope are placed into the abdominal cavity. The laparoscope illuminates the surgical field and sends a magnified image from inside the body to a video monitor giving the surgeon a close-up view of organs and tissues. The surgeon watches the live video feed and performs the operation by manipulating the surgical instruments placed through the trocars.
The first step in laparoscopic surgery is to make a small incision to access the abdomen and create pneumoperitoneum. Pneumoperitoneum is the insufflation of the abdominal cavity with carbon dioxide gas. Insufflation with gas creates a working space in the abdomen necessary for laparoscopy. Once a proper working space has been created, surgical instruments can be inserted for performing a laparoscopic procedure. This process of penetrating the abdomen and creating pneumoperitoneum prior to insertion of other instruments is called first entry. There are many different ways to achieve pneumoperitoneum. One option is using a Veress needle. A Veress needle is approximately 12-15 centimeters long with a diameter of approximately 2 millimeters. The surgeon inserts the spring-loaded needle into the abdomen of the patient after making a small incision. When the needle breaches the inner abdominal space, the spring-loaded inner stylet springs forward to cover the sharp needle in order protect internal organs. The surgeon relies on the feel and sound of the needle and spring for proper placement. Once proper entry is confirmed, carbon dioxide is introduced through the Veress needle and into the abdominal cavity of the patient expanding the abdomen to creating a working space.
Another option is a Hasson technique or cut down technique in which the surgeon makes an initial incision at the umbilicus and the tissue is bluntly dissected. A suture is placed on either side of the incision into the fascia layer to help hold the device in place. The supraperitoneal tissue is dissected away and the peritoneum is incised to enter the abdominal cavity. At this point, a Hasson trocar is inserted into the incision. The Hasson trocar has a blunt tip with suture ties and/or a balloon to hold it in place. After the trocar is placed into the incision, the device is secured with sutures and/or the balloon and carbon dioxide gas is pumped into the patient through the trocar to achieve pneumoperitoneum.
Another option is direct trocar entry. In this option, the surgeon uses a bladed or non-bladed trocar. The trocar can be used optically in which a specialized trocar is configured to receive a laparoscope and a laparoscope is inserted into the trocar before entry in order to view the penetration as it occurs. Also, the trocar may be use non-optically without a laparoscope inside. After the initial incision is made, the trocar is placed through the layers of the abdomen. Since the camera is present, all of the layers of the abdominal wall can be observed during penetration. Once the surgeon sees that he or she has broken through the peritoneum, penetration can halt, the obturator tip of the trocar pulled back slightly or removed entirely and insufflation can commence by pumping carbon dioxide gas in through the cannula to create pneumoperitoneum.
Another option involves a specialized first entry trocar such as the FIOS® first entry trocar made by Applied Medical Resources Corporation in California. Like optical direct trocar entry, a laparoscope is inserted into the FIOS® trocar and the abdominal wall layers are observed during insertion into the abdominal cavity. The specialized FIOS® trocar has a small vent hole in the tip such that instead of requiring that the obturator of the trocar be pulled back or removed completely to introduce carbon dioxide through the cannula, carbon dioxide gas is introduced through the small vent hole in the tip of the obturator with the camera in place. Because carbon dioxide can be introduced through the tip, the FIOS® trocar does not have to penetrate as deeply into the abdominal cavity as a traditional trocar, thereby, affording internal organs greater protection before insufflation can commence. Also, because the obturator does not have to be pulled back or removed, observation via the inserted camera can take place at the point of insufflation.
In addition to the above options for entering the abdominal cavity, generally, there are two common places on the abdomen that a surgeon must know how to enter. The most widely used location for first entry is the umbilicus. The umbilicus is a natural weakening in the abdomen where the umbilical cord was attached in the womb. In this part of the abdomen, there are no rectus muscles, arteries or veins so it is generally easier to reach the abdominal cavity. Additionally, the umbilicus is typically an easy place to hide a scar. When surgeons use the umbilicus as an entry site, particularly for the Hasson technique, clamps are often used to grab the base of the umbilicus and the umbilicus is inverted. At this point, an incision is made and the surgeon cuts down as desired and inserts the trocar or Veress needle. With optical entry, the surgeon is able to see all the layers of the abdominal wall. In this location of penetration, they are able to see the fatty tissue, linea alba, transversalis fascia and, finally, the peritoneum. Additionally, when entering at the umbilicus, the umbilical stalk should also be visible. The stalk is what remains of the umbilical cord and it stretches from the skin making up the umbilicus to the peritoneal layer.
If a patient has had a previous surgery and adhesions are suspected or a hernia is present at the site of the umbilicus, first entry may need to occur at another location. In this case, the surgeon will often enter from the left upper quadrant since there is less chance of damaging a vital organ in this location. The left upper quadrant is different from the umbilicus region in that there are muscle layers. The rectus abdominus muscles run parallel with the patient's abdomen and are found on either side of the patient's midline. Underneath the rectus abdominus muscles run the inferior epigastric veins and arteries which the surgeon must be careful to avoid. When a surgeon is entering the upper quadrant of the abdominal cavity optically, he or she is able to see the skin, fatty tissue, anterior rectus sheath, rectus abdominus, the epigastric vein, which runs through the posterior rectus sheath, and finally, the peritoneum. If the left upper quadrant is not an ideal position for a port, the surgeon may choose to enter at another location such as sub-xiphoid where subcutaneous fat, rectus sheath and peritoneum are present.
Since there are many options for first entry, it is important that surgeons have a way to learn and practice the various techniques. There is a need for an anatomical model of the umbilical region and surrounding abdomen that is anatomically correct and includes all the layers of the abdominal wall as well as the veins and arteries that run through the wall. Not only does the model have to be anatomically correct, but also, the model must provide a realistic aural and tactile sensation. For example, when using a Veress needle, two pops are generally felt as the surgeon pushes the needle through the abdominal wall. For optical entry, the surgeon needs to view all of the appropriate tissue layers in the abdominal wall. For entry through the umbilicus, the surgeon must be able to grasp and invert the umbilicus. Also, the model may be able to be used with all four first entry techniques and at multiple (umbilical and upper left quadrant at minimum) entry sites.